(a) Field of the Invention
The present invention relates to a vaccine composition containing a promoter peptide, and more specifically to a vaccine containing a specific peptide that promotes the vaccination effect.
(b) Description of the Related Art
The essence of the immune system is its capacity to recognize foreign substances, or antigens. Various antigen-specific B-lymphocytes are on the alert, and when a foreign antibody invades the body, certain B-lymphocytes are activated upon recognizing the antigen to trigger the so-called primary immune response, which involves the transfer of intracellular signals and secretion of a specific antibody against the antigen. Some of the activated B-lymphocytes persist as memory cells which retain the capacity to produce the antibody upon stimulation by the same antigen. Thus when the antigen is encountered a second time, a secondary immune response takes place, and memory cells quickly produce a large amount of the antibody.
Injection of a vaccine containing an antigen artificially induces the immune response by stimulating the immune system with the injected antigen. In this case, an immune activator such as alum (aluminum hydroxide) or Freund's adjuvant is added to nonspecifically enhance the immune response to the vaccine.
The present inventors have previously reported that the peptide of SEQ ID NO: 1 activates monocytes, B-lymphocytes, and neutrophils (Beak, S. H. et al., J. Biol. Chem., 271, 8170 (1996)). This peptide enhances the activity of phospholipase C (PLC), an intracellular signal transduction protein in B-lymphocytes, and the activated PLC catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into two intracellular second signal messengers, inocytol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). The IP3 induces an increase in intracellular free calcium concentration ([Ca2+]I), while DAG directly activates protein kinase C (Nixhizuka Y., et al., Science, 233, 305 (1986)). It has been reported that the peptide induces the intracellular calcium [Ca2+]I release in a human B-lymphocyte cell line U266 (Baek, S. H., et al., J. Biol. Chem., 271, 8170 (1990)) and activates the cellular signal pathway by binding with a specific receptor protein in the cell membrane of the U266 cell line (Seo, J. K., et al., J. Immunol., 158, 1895(1997)). Further, the peptide is capable of stimulating neutrophils to increase the production of active oxygen species, which enhances the sterilization effect (Bae, Y. S., et al., J. Leukoc. Biol., 65, 241 (1999)), and induces chemotaxis of human neutrophils.
The Hepatitis C virus (HCV), discovered in 1989, is an RNA virus, and chronic infection by the virus can lead to hepatomas. However, at present, there is no effective cure for individuals infected with HCV, and even the identity and specificity of HCV have not been completely understood. Therefore, a need to develop an improved vaccine which can prevent various diseases such as HCV infection has continued to exist.